Densities, surface tensions, and refractive indices of the binary water + 1,3-propanediol system were measured at temperatures of 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15 K and at 1,3-propanediol mass fractions of 0.00, 0.10, 0.20, 0.40, 0.60, 0.80, and 1.00, respectively. The measured data were well correlated with the simple polynomial equations. The average absolute deviations were found to be 0.123% for density, 0.77% for surface tension, and 0.045% for refractive index.